Employee Retirement Benefits - Net Periodic Income Cost Regulatory Assets (Details) - Pension Benefits [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Unrecognized losses (gains)	$ 216	$ (120)
Amortization of prior service cost	1	1
Total	$ 217	$ (119)

The amortization of prior service cost component of net periodic benefit (income) cost recognized during the period in regulatory assets (liabilities).

No definition available.

Name:	nee_DefinedBenefitPlanAmortizationOfPriorServiceCostBenefitRecognizedInRegulatoryAssetsLiabilities
Namespace Prefix:	nee_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration